Use of Gamma Ray Spectroscopy Measurements for Assessment of the Average Effective Dose from the Analysis of 226Ra, 232Th, and 40K in Soil Samples

Abstract

The activity concentrations of the natural radionuclides: 238Ra , 232Th, and 40K were measured in soil samples collected from two districts of the Punjab. A HPGe detector, based on high-resolution gamma spectrometry system was used for their measurement. The range of activity concentrations of 226Ra, 232Th, and 40K in the soil from the studied areas varied from 25 Bq·kg-1 to 42 Bq·kg-1, 72 Bq·kg -1 to 130 Bq·kg-1, and 229 Bq·kg-1 to 385 Bq·kg -1 with overall mean values of 32 Bq·kg-1, 91 Bq·kg -1,and 289 Bq·kg-1, respectively. Radium equivalent activities were calculated for the samples to assess the radiation hazards arising due to the use of these soils in the construction of dwellings. The absorbed dose rate calculated from activity concentration of 226Ra, 232Th, and 40K ranges between 12 and 19, 45, and 81, and 9 and 16 nGy·h-1, respectively. The total absorbed dose in the study area ranged from 70 nGy·h-1 to 111 nGy·h-1 with an average value of 84 nGy·h-1. The calculated values of external hazard index (Hex) for the soil samples ranged from 0.41 to 0.67. Since these values are lower than unity the soil from these regions is safe and can be used as a construction material without posing any significant radiological threat to population according to the Radiation Protection 112 (European Commission, 1999) report. The corresponding average annual effective dose for indoors and outdoors was 0.41 and 0.11 mSv, respectively.